It is known to produce so-called caustic magnesium oxide from magnesium compounds, like for example, magnesium carbonate, which caustic magnesium oxide is the basic substance of a binding material, which is able to bind considerable amounts of mineral or organic fillers. Moreover, the caustic magnesium oxide is mixed with aqueous magnesium salt solutions and fillers, and in viscous form used as cement or pavement. The binding properties of these viscous masses results essentially because oxide compounds are formed from the magnesium oxide and the mixed magnesium salts which are in dissolved form, the oxide compounds causing strengthening of the viscous mass. When, instead of the magnesium salts, magnesium chloride is preferably used, magnesium oxychloride is formed. Such mixtures consisting of magnesium oxide, water and magnesium chloride are known under the designation "Sorel Cement" or "Magnesia Mortar".
In DT-PS No. 739,164 it has already been described that for the so-called magnesia cement employing magnesium oxide (MgO) also magnesium hydroxide can be used, when a magnesium chloride solution of such concentration is used therewith that the magnesium chloride concentration in the mixture is between 21 and 27 weight percent, under addition of water which adheres to magnesium hydroxide and is chemically bound therein. Considering this method the speed of formation of oxychlorides can be quickened, when active magnesium oxide is used. However, this method is effected with difficulties, that magnesium oxide or magnesium hydroxide or magnesium chloride solution can be mixed only in situ, the value of the aspired products depends essentially upon careful observance of proportions and the concentration of magnesium chloride solution as well as on the carefulness with which the mixing is performed. There is also the requirement that this method be performed only by particularly skilled workers.
DT-PS No. 832,565 discloses dry mixtures for the production of magnesium oxide cements, a technical improvement. These mixtures are obtained from aqueous mixtures of magnesium hydroxide and magnesium chloride solution, which mixtures are concentrated after the mixing to such an extent that predominantly magnesium hydroxide and magnesium chloride are obtained in free form in addition to the obtained oxychloride. The dry mixtures are, after size reduction, if necessary after addition of filler materials, stirred and worked up with water. According to the desired composition magnesium oxide and/or magnesium chloride solution can be added to the mixture.
This procedure is supplemented by DT-PS No. 839,622 in that pastes of magnesium hydroxide and 10 to 30% magnesium chloride solution are used, wherein the mixture contains 100 parts by weight magnesium hydroxide, 100 to 700 parts by weight magnesium chloride solution. For the processing of this paste corresponding amounts of magnesium hydroxide or, respectively, oxide and water are to be added.
In the "Publication of the Research Community on Building and Living" (1966), No. 80, page 57, under the title "Pavement in Above Surface Structures", it is stated that the mixing proportions in parts by weight of magnesium chloride (MgCl.sub.2) to magnesium oxide (MgO) should be approximately about 1:2.5 to 1:3.5; however, in no case less than 1:2.
As already mentioned, the manufacture of "sorel cement" or respectively "magnesia pavement mass" requires either particularly experienced trained workers, who at the building site determine the ratio of components, as well as supervise their observance, or under considerable expense and energy a dry mass consisting of magnesium oxichloride, magnesium oxide, magnesium hydroxide and magnesium chloride dry product is manufactured, which can be mixed with water prior to use.
In dependence on the composition and evaporation processes, these dry products contain the mentioned components in permanently altering compositions, so that prior to their use small scale tests must be performed, following of which outcome the proportion of dry measure to water in each individual case must be determined.
It is the object of the invention to create a dry product without high expenditure of energy, which dry product is obtained in permanently uniform compositions and can be worked up at the building site by mixing with water in permanently constant ratio.